[Illustration: Fig. 21 a, b, c.--_Glenodinium compressa_, n. sp.]


Glenodinium cinctum Ehr. Fig. 22.

The body is globular, smooth, and homogeneous. Brown chromatophores
arranged radially, each in the form of a cone, the base of which
rests against the shell while the points turn inward. A bright-red
eye-spot may or may not be present; when present it is placed near
the junction of the two furrows. The longitudinal furrow is small.
Fresh water and salt.

Length and diameter the same, 21µ.

This species was observed by Peck '93.


[Illustration: Fig. 22.--_Glenodinium cinctum_.]


Genus PERIDINIUM Ehr. '32, Stein '83.

(Claparède & Lachmann '58; Bergh '81; Pouchet '83; '85; Gourret '88;
Bütschli '86.)

The form is globular, ovoid or elongate, the apex frequently drawn
out into a long tube. The transverse and longitudinal furrows are
quite distinct, the former having often a spiral course about the
body. The two halves of the body are similar, the posterior being
somewhat shorter; the anterior half has seven equatorial plates, an